Low-Field MR-Guided Frameless Stereotactic Biopsy for Intracerebral Lesions

Aim: The aim of our study is to present the technique of intraoperative low-filed magnetic resonance imaging (ioMRI) for stereotactic brain biopsy in various intracerebral lesions.

Methods: Between 2006 and 2011, 78 patients underwent stereotactic brain biopsies using the PoleStar ioMRI system (N-20 and N-30, Medtronic Navigation, Louisville, USA) and data were evaluated retrospectively. Biopsy technique included ioMRI preoperatively, followed by insertion of the biopsy cannula in the lesion based on the calculated trajectory. ioMRI confirmed accurate placement before biopsy for neuropathological examination.

Results: In all patients stereotactic biopsy was possible with a mean overall surgery time of 86.2 minutes (SD 28.6) including a mean intraoperative imaging time of 12.14 minutes (SD 2.7). Mean hospital stay was 11.6 days (SD 4.6). In 97.4% of patients (n = 76) histological diagnosis was conclusive representing 58 brain tumors, 10 infections, 5 demyelinating diseases, 2 amyloid angiopathy associated hematomas, and 1 radiation necrosis. Mean lesion volume in T1 with contrast (n = 68) was 71.7 cm³ (range 1.4 to 350.1 cm³, SD 70.9) and in lesions without T1-contrast enhancement (n = 10) T2-mean lesion volume was 52.5 cm³ (range 4.8 to 187.3 cm³, SD 53.4). Mean distance cortex surface to the lesion was 3.4 cm (range 1.1 to 6.2 cm, SD 1.2). One patient suffered from a postoperative wound dehiscence, no patients suffered from a clinically or radiologically significant hemorrhage after surgery and no intraoperative complications occurred.

Conclusions: Frameless stereotactic biopsy with a low-field ioMRI was accurate to diagnose a variety of intracerebral lesions with a rare complication rate for the patient and both acceptable surgery and hospital stay time.